The invention described and claimed herein is related to U.S. Application Ser. No. 737,306 filed May 23, 1985, now U.S. Pat. No. 4,614,076, issued Sept. 30, 1986 which is incorporated herein by reference in its entirety. This invention relates to methods and apparatus for the production of flexible packaging wherein each individual package contains a sealed controlled quantity of a non-solid substance. Representative of such substances are ointments, gels and salves, for example, More particularly, this invention relates to the continuous surface treatment of at least one web forming the flexible packaging so as to modify the surface thereof to enhance the sealing properties in the formation of the packages of the invention. In this connection, the approach may include intermittent or continuous formation of the packages.
In flexible packaging of the kind to which this invention relates it is important that a precise controlled quantity of material be contained in each individual package if, for example, the ointment, gel or salve is a medication requiring a precise quantity for later medical application to a patient. Such applications include, for example, transdermal medication in which a flexible package includes a special membrane with an adhesive surface, or a surface with a peripheral adhesive border, which may be applied to the skin of a patient for a controlled administration of a medication over a period of time. Such flexible packages include a peel-off film over the adhesive surface, which the user peels off immediately prior to applying the package to his skin.
With the invention herein, methods and apparatus are provided for the continuous or intermittent and rapid production of a plurality of such flexible packaging containing a non-solid material by joining the two webs together in the nip of sealing rolls or platen dies, depending upon which form of packaging machinery is being utilized. This is achieved specifically with the invention here with two dissimilar materials. Ordinarily, such materials will not provide a proper seal. It is within the purview of this invention to provide such continuous packaging using dissimilar thermoplastic by exposing one web to be joined subsequently in a heated nip with a corona discharge so as to modify the surface chemistry thereof to adhere in proper sealing relationship to the opposing web.
That is, a plurality of such packages may be formed simultaneously across the width of the webs being joined together in the roller nip in one form of packaging of a pair of rollers which cooperate to provide, automatically and simultaneously, for the formation, and sealing of each individual flexible package in the webs. Alternatively, opposed platens may form the packages by cooperative operation with each other. By utilizing the continuous corona exposure, a backing web of a single thermoplastic material may be used rather than a laminate including a separate material for adherence to the opposing web, or bonding agents, both expensive propositions.
Thus, flexible packages may be produced on a continuous basis in a much more simplified and economical manner. The invention contemplates the use of cooperating sealing rollers in which one roll includes pockets for forming the individual flexible packages cooperating with a second roll which provides a proper pressure at the nip of the rolls in order to form the individual packages across the width of the webs being joined. As will be understood by practitioners of the packaging art opposed platens may be used, also, wherein one includes pockets and the other provides flat plate pressure.
Transdermal membranes utilized for packages of the kind discussed herein have properties specifically selected to produce the desired passage of medication, once the package is opened, and the membrane adhered to the skin. However, the properties which provide this desired, controlled passage of medication are adverse to sealing properties required in the laminated package as produced and prior to use. The invention here provides a chemical surface modification so as to provide simultaneously the desired sealing and medication passage properties.
Thus, the webs contain thermoplastic resin materials which may be joined and sealed under the application of heat and pressure. In one representative form of machinery to be described below, crimp rolls which cooperate to provide the sealed packaging on a continuous basis are heated in order to provide the appropriate sealing of the two webs together during the simultaneous forming, and sealing of the flexible packages. Once the two webs are joined together, the packages may be cut from the web by opposed cooperating rotary die rolls.
Before describing this invention in more detail, it may be well to note that silicone rubber membranes may be used herein for the actual transmission of medication, once a patch is in place on the skin of a patient. Such materials include generally a polydimethyl siloxane copolymer (silicone film), such as LSR 44210 SILASTIC.TM. a product of Dow Corning Corp., Midland, Mich. Also used experimentally is Dow Experimental #E6669-39 silicone sheeting. The backing material, which forms the opposite side of the patch and provides "body" therefor may be, for example, a polyester film laminated to a ethylene acrylic acid copolymer film. With respect to the silicone membrane mentioned above, the very properties that make it appropriate for dispensing medication in a controlled manner, make the material less desirable for sealing to a backing film. Thus, the invention herein solves that by modifying the surface to make the membrane have two diametrically opposite but desired properties for accommodating a transdermal patch application.
The flexible packaging procedures involved herein apply to a variety of different materials which may be packages, as long as they contain a liquid component. That is, ointments, gels, salves and even oils may be contained within the flexible packaging herein, as long as the material involved will, when dropped on the web and prior to being sealed, hold a momentary selfcontained body until such time as the material is properly joined in the flexible packaging formed by the methods and apparatus herein. It will be understood, furthermore, that a variety of different film materials comprised of thermoplastics may be utilized in the processing of the invention herein for forming the webs which are joined together to produce the flexible packaging. For example, polyvinyl chloride, polyvinylidene chloride, polyesters, polyethylene and polypropylene are all materials which may be utilized.
With the foregoing and additional objects in view, this invention will now be described in more detail, and other objects and advantages thereof will be apparent from the following description, the accompanying drawings, and the appended claims.
As purely illustrative of apparatus which may be used for carrying out the process of this invention, one may note the attached drawings in which a schematic illustration of apparatus for carrying out the invention is shown together with a representative package which may be formed in accordance with this invention.